This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. High field EPR is a useful tool for investigating change transfer complex formation between unsubstituted o-semiquinones and different organic compounds (quercetin, cyclodextrin, albumin) The formation of charge transfer complexes was verified by observation of the optical spectrum of the charge transfer band. The high-field EPR spectra reveal for the first time a well-resolved g-tensor with a unique fingerprint for every type of complex. Subsequent work will use high-field EPR and quantum chemistry in order to calculate the exact structure of the complex in order to develop a spectral library for identifying various biological molecules containing charge transfer complexes.